This invention is generally related to rule assemblies and more particularly to rule assemblies of the spring retractable type.
A typical retractable tape rule assembly includes an elongated thin metal rule blade that is mounted on a reel rotatably disposed within a housing assembly. The rule blade is retracted into the housing assembly for storage by coiling it about the reel. To measure a workpiece, a length of the rule blade is pulled out of the housing assembly to span the distance to be measured and the blade is held against the workpiece so that gradation lines and numbers printed on the blade can be read against a point on the workpiece. To measure a distance between two objects or surfaces, typically the free end of the blade is temporarily secured to one object and the tape is unwound from the reel to span the distance between the objects.
It is important for a tape assembly user measuring a workpiece working alone to have a way of quickly and conveniently removably securing the free end of the blade to the workpiece to allow the blade to be easily extended and then to hold the gradations on the blade against the workpiece. Similarly, it is important for a single user measuring a distance between objects to have a way of quickly and conveniently removably securing the free end of the blade to the one object to allow the blade to be easily extended and to hold the blade straight and steady (particularly when a portion of the extended blade is unsupported) while taking a measurement. Usually a blade hook is provided on the end of the rule blade to provide the user with means of securing the free end of the blade to the object or workpiece.
Prior art blade hooks provide the user with only a limited ability to hookingly engage the free end of a blade with an object or workpiece, however. A typical prior art blade hook includes a simple flange-like structure that extends downwardly at essentially a right angle from the free end of the blade. The simple flange-like structure is essentially a square metal structure having a maximum width that is approximately equal to the width of the blade in its extended condition. The flange-like structure secures the free end of rule blade to the workpiece by, for example, hooking over an edge or corner of the workpiece. This simple flange-like structure provides no structure above the surface of the blade to hookingly engage the workpiece or object and provides little or no structure beyond the transversely spaced, longitudinally extending edges of the blade to engage the workpiece.
A need exists for a blade hook that provides structure extending upwardly from the free end of the blade and outwardly on each side of the blade as well as downwardly from the free end of the blade to provide the tape assembly user with greater ability to securely anchor the free end of blade while taking a measurement.
Furthermore, is well-known that the metal rule blades of retractable tape assemblies have a generally concavo-convex cross-section when in the extended condition. When the concave side of the blade is placed against the workpiece, this cross sectional configuration tends to place the opposite longitudinally extending edges of the blade in spaced relation to the surface of the workpiece on which the blade is resting. This can make it difficult to read a measurement off of the blade. This is particularly a problem when the curve height of the cross section of the extended blade is relatively high. It is frequently easier to read a measurement from a blade having a high cross sectional curve height by tipping or tilting the extended blade in a transverse direction so that a longitudinally extending edge of the blade is nearer to or is touching the workpiece. Simple flange blade hooks are not suited to hold the blade in a tilted position because the flange portion extends downwardly from the end of the blade and does not extend appreciably beyond the opposite longitudinally extending edges of the blade. Consequently, there is a further need for a hook member that provides structure extending beyond the opposite longitudinally extending edges of the blade which structure can provide the user with the ability to easily hold the blade in a tilted or tipped position to facilitate reading a measurement from the rule blade.
An objective of the present invention is to fulfill the needs expressed above. In accordance with the principles of the present invention, this objective is achieved by providing a rule assembly that includes a housing assembly and a reel rotatably mounted in the housing assembly. An elongated blade formed of a ribbon of metal is mounted on the reel. One end of the blade is connected to the reel. The opposite end of the blade extends tangentially from the reel outwardly through an opening in the housing assembly. The blade has a xe2x80x9cnormalxe2x80x9d concavo-convex cross-sectional configuration when it is extended and has a flat cross-sectional configuration when it is wound about the reel. The coiled blade is disposed about the reel in an abutting volute coil formation. An end hook member is mounted on the free end of the blade. The end hook member is preferably formed of sheet metal of a predetermined thickness and includes a concavo-convex mounting portion and a U-shaped hook portion. The U-shaped portion is bent at a generally right angle from one end of the mounting portion. The mounting portion of the end hook member is secured for limited sliding engagement on a concave side of the blade. This limited sliding movement allows the user to take an accurate measurement regardless of whether an exterior surface of the U-shaped hook portion is in abutting engagement with the workpiece or an interior surface of the U-shaped hook portion is in abutting engagement with the workpiece. The U-shaped hook portion includes a bight section that extends downwardly from a convex side of the free end of the blade and spaced leg sections that extend both outwardly beyond transversely spaced corners of the free end of the blade and upwardly above the concave side of the blade. Preferably, the transversely spaced corners of the free end of the blade are mitered inwardly from opposite edges of the blade and the leg sections extend both upwardly and outwardly beyond the mitered corners and the opposite edges.
In one preferred embodiment of the invention, retraction of the blade is spring powered. Specifically, a coil spring that is formed of a ribbon of metal is mounted between the housing assembly and the reel. The spring rotates the reel to wind the blade around the reel. A manually actuated blade holding assembly is provided to hold the blade in and then to release the blade from an extended position.
The downwardly extending byte portion of the hook member allows the blade to be, for example, hooked over an edge or corner of a workpiece (or other structure below the convex side of the blade) when the blade is placed on the workpiece with the convex side of the blade against the same. The leg portions of the U-shaped portion of the hook member allow the blade to be anchored to structure above the concave surface of the blade and/or to structure generally on one or both sides of the blade. The leg portions also allow the worker to easily hold the blade at an angle with respect to a surface on the workpiece to hold a longitudinal edge of the blade against the surface so that a measurement can be easily read.
It is a further object to provide a retractable rule assembly having the hook member previously described with any combination of the following additional features:
1. A retractable rule assembly wherein the elongated blade has a width in the flattened configuration thereof having a dimension within the range of 1.10xe2x80x3-1.5xe2x80x3, a height in the concavo-convex configuration thereof having a dimension within the range of 0.25xe2x80x3-0.40xe2x80x3 and a thickness in either configuration thereof having a dimension within the range of 0.0045xe2x80x3 to 0.0063xe2x80x3.
2. A retractable rule assembly wherein the concavo-convex cross-sectional configuration of the blade includes an arcuate central section having a predetermined radius of curvature and integral arcuate end sections each having the same radius of curvature, the radius of curvature of the central section being a dimension within the range of 0.35xe2x80x3 to 0.60xe2x80x3 and the radius of curvature of each end section being a dimension within the range of 1.0xe2x80x3 to 5.0xe2x80x3.
3. A retractable rule assembly wherein a relatively short free end portion of the blade has a clear film of plastic material adhered to a concave side thereof.
4. A retractable rule assembly wherein the metal ribbon of the spring has a width which is 95%-120% of the width of the metal ribbon of the blade.
5. A retractable rule assembly wherein the housing assembly includes a pair of cooperating housing members, each including an end wall having a peripheral wall extending from a periphery thereof and terminating in a free edge, the housing members being fixed together with their free edges interengaged by a plurality of bolts extending through one of the housing members and threadedly engaged in the other at spaced positions adjacent the peripheral walls thereof and by a fixed reel spindle having a non-circular interengaging recess-projection connection at each end thereof with the central interior of the adjacent end wall, each end of the spindle being interiorly threaded to threadedly receive a bolt therein extending through a central hole in the adjacent end wall and the recess-projection connection between the central hole and threaded interior.
6. A retractable rule assembly wherein the housing assembly includes a fitment defining a part of the housing assembly opening adjacent a convex side of the blade, the fitment having a plurality of tangentially extending transversely spaced elongated ridges defining surfaces for engaging the convex side of the blade extending tangentially from the reel to said housing assembly opening.
7. The housing assembly includes a bottom wall having an exterior portion at an end position adjacent the housing assembly opening which projects below the exterior surface portion extending therefrom toward an opposite end to provide a finger grip enhancing configuration.
8. The housing opening has a height dimension which exceeds the height dimension of the blade an amount that is at least approximately equal to the amount the hook portion extends below the bottom end surface of the housing assembly at the housing opening.
9. The blade has a blade width, thickness and height of concavo-convex curvature sufficient to enable the blade to stand out arcuately a length measured along the blade of approximately 11 feet with a horizontal linear length of standout thereof greater than 97% of the arcuate length of standout.
In the broadest aspects of the present invention, it is an object to provide any known rule assembly with a hook member constructed according to the principles of the present invention.
These and other objectives, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.